Hybrid compressor system

ABSTRACT

A hybrid compressor system has a hybrid compressor for compressing refrigerant. The compressor is selectively driven by one of a first drive source and a second drive source. The hybrid compressor system also includes a first one-way clutch, a driver for driving the second drive source, a sensor for detecting a rotational state of the first drive source and a controller. The first one-way clutch is arranged on a first power transmission path between the compressor and the first drive source for permitting power transmission from the first drive source to the compressor. The controller is electrically connected to the driver and the sensor. When a drive source of the compressor is switched from the second drive source to the first drive source, the controller orders the driver to stop the second drive source after the rotation of the first drive source is detected.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a hybrid compressor systemincluding a hybrid compressor, a drive source of which is switchedbetween an electric motor and an engine for driving a vehicle, forcompressing refrigerant.

[0002] A hybrid compressor in an air conditioning system for a vehicleis disclosed in Japanese Unexamined Patent Publication No. 2002-67673.An electromagnetic clutch is arranged on a power transmission pathbetween the engine and the hybrid compressor. When a drive source of thehybrid compressor is switched from an electric motor to an engine, theelectromagnetic clutch is switched on or connected after a rotationalspeed of the electric motor becomes equal to a rotational speed of theengine.

[0003] Therefore, even when the drive source is switched, the hybridcompressor continuously compresses refrigerant. Namely, air conditioningis continuously conducted by the air conditioning system. Therefore,comfortable cooling feeling can be offered. Furthermore, since the drivesource is smoothly switched, unpleasant shock caused by a rotationalspeed differential between the hybrid compressor and the engine uponswitching on the electromagnetic clutch can be avoided.

[0004] However, a complicated control, in which the electric clutch isswitched on after the rotational speed of the electric motor becomesequal to the rotational speed of the engine, is required. Therefore, acomputing load on a control device increases.

SUMMARY OF THE INVENTION

[0005] The present invention provides a hybrid compressor system thatsmoothly switches a drive source of a hybrid compressor from an electricmotor to an engine without a break of air conditioning and a complicatedcontrol.

[0006] In accordance with a preferred embodiment of the presentinvention, a hybrid compressor system has a hybrid compressor forcompressing refrigerant, a first drive source, and a second drivesource. The first drive source is operatively connected to thecompressor through a first power transmission path. The second drivesource is operatively connected to the compressor through a second powertransmission path. The compressor is selectively driven by one of thefirst drive source and the second drive source. The hybrid compressorsystem also includes a first one-way clutch, a driver for driving thesecond drive source, a sensor for detecting a rotational state of thefirst drive source and a controller. The first one-way clutch isarranged on the first power transmission path between the compressor andthe first drive source for permitting power transmission from the firstdrive source to the compressor. The controller is electrically connectedto the driver and the sensor. When a drive source of the compressor isswitched from the second drive source to the first drive source, thecontroller orders the driver to stop the second drive source after therotation of the first drive source is detected.

[0007] The present invention also provides a method for switching adrive source of a hybrid compressor from a stopped state of an enginefor running a vehicle to a normal running state. The compressor isoperatively connected to the engine through a power transmission pathand selectively driven by one of the engine and an electric motor. Astarter motor is operatively connected to the engine. A preferred methodincludes the steps of providing a one-way clutch on the powertransmission path between the compressor and the engine, driving thecompressor by the electric motor during an idle stop of the vehicle,detecting a rotational speed of the engine, driving the electric motorsuch that the electric motor drives the hybrid compressor at a secondpredetermined speed when the rotational speed of the engine is detected,and stopping the electric motor when the detected rotational speed ofthe engine exceeds a predetermined value. The predetermined value rangesbetween a third predetermined rotational speed of the engine thatcorresponds to a first predetermined rotational speed of the compressorand a fourth rotational speed of the engine that corresponds to thesecond predetermined rotational speed of the oompressor. The compressoris driven at the first predetermined rotational speed when power istransmitted from the starter motor to the compressor through the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The features of the present invention that are believed to benovel are set forth with particularity in the appended claims. Aspect ofthe invention may best be understood by reference to the followingdescription of the presently preferred embodiments together with theaccompanying drawings in which:

[0009]FIG. 1 is a longitudinal cross-sectional view of a compressor;

[0010]FIG. 2 is a flow chart Illustrating control for switching a drivesource of the compressor from an electric motor unit to an engine;

[0011]FIG. 3(a) Is a timing graph illustrating the drive source of thecompressor; and

[0012]FIG. 3(b) is a timing graph illustrating rotational speeds of theengine and the electric motor unit regarding the control In FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A preferred embodiment according to the present invention will bedescribed now. As shown in FIG. 1, a hybrid compressor C, whichconstitutes a refrigerating cycle in an air conditioning system for avehicle, has a housing 11 for compressing refrigerant. A piston typevariable displacement compression unit 12 is accommodated in the housing11. The compression unit 12 includes a rotary shaft 13, a swash plate14, a pair of shoes 15 and a piston 16. The swash plate 14 is rotated bythe rotation of the rotary shaft 13. The rotational movement of theswash plate 14 is converted into the reciprocating movement of thepiston 16, thereby compressing a refrigerant gas.

[0014] A power transmission mechanism Pr is arranged at one end of thehousing 11 outside the housing 11, such that the axis of the powertransmission mechanism PT corresponds to the axis of the rotary shaft13, for transmitting power to the rotary shaft 13. The powertransmission mechanism PT includes a pulley 17 and an electric motorunit 38 as an electric motor or a second drive source.

[0015] The pulley 17 is rotatably supported by the housing 11. Thepulley 17 transmits power from an engine E (internal combustion engine)as a first drive source for driving a vehicle to the rotary shaft 13. Astarter motor S is operatively coupled to the engine E for starting upthe engine E. During a starting period of the engine E by the startermotor S, or during a time when the starter motor S starts the engine E,power is transmitted from the starter motor S to the pulley 17 via theengine E. In the present specification, a rotational state of the engineE includes not only a independent rotation of the engine E but also adependent rotation of the engine E when driven by the starter motor S.

[0016] The electric motor unit 38 is utilized to drive the rotary shaft13 when the engine E is in a stopped state. The air conditioning systemincludes the electric motor unit 38. Therefore, air conditioning iscapable of being continuously conducted even when the engine E is in thestopped state. The air conditioning system in the present preferredembodiment is suitable for an idle stop vehicle and a hybrid vehicle.

[0017] Next, an exemplary power transmission mechanism PT will bedescribed. The rotary shaft 13 of the compression unit 12 is rotatablysupported by the housing 11 and protrudes thorough the front wall of thehousing 11 to the outside of the housing 11. A boss 35 protrudes fromthe front wall of the housing 11. The boss 35 receives the rotary shaft13 through a bearing.

[0018] The pulley 17 includes a first pulley member 18 and a secondpulley member 19. The first and second pulley members 18 and 19 arearranged in the identical axis. A belt 20 engages with the outerperiphery of the first pulley member 18 from the engine E. A bearing 25is interposed between the first pulley member 18 and the boss 35 of thehousing 11. The first pulley member 18 is rotatably supported by theboss 35 of the housing 11 through the bearing 25.

[0019] A hub 30 is fixed to the front end of the rotary shaft 13. Afirst one-way clutch 31 is interposed between the hub 30 and the secondpulley member 19. Namely, the first one-way clutch 31 is arranged on afirst power transmission path between the rotary shaft 13 and the engineE. The second pulley member 19 is supported by the hub 30 through thefirst one-way clutch 31. The first pulley member 18 is connected to thesecond pulley member 19 through a power-transmitting pin 28 and a rubberdamper 29. The power-transmitting pin 28 functions as a breaking typetorque limiter. The rubber damper 29 helps to compensate the variationin the transmitted torque between both the pulley members 18 and 19.

[0020] The first one-way clutch 31 includes a roller type clutchmechanism 31 a and a bearing 31 b. With respect to a predeterminedrotational direction, the clutch mechanism 31 a permits powertransmission from the second pulley member 19 to the hub 30, and blockspower transmission from the hub 30 to the second pulley member 19. Whenthe electric motor unit 38 is in a stopped state and the first pulleymember 18 is rotated by the drive of the engine E in the predeterminedrotational direction, the second pulley member 19 is rotated through thepower-transmitting pin 28 and the rubber damper 29 in the predeterminedrotational direction. As a result, the rotational power of the secondpulley member 19 is transmitted to the rotary shaft 13 through the firstone-way clutch 31 and the hub 30.

[0021] On the other hand, when the engine E is in the stopped state andthe rotary shaft 13 is rotated by the electric motor unit 38 in thepredetermined rotational direction, the rotational power of the rotaryshaft 13 is transmitted to the first one-way clutch 31 through the hub30. However, since the clutch mechanism 31 a of the first one-way clutch31 blocks the power transmission from the hub 30 to the second pulleymember 19, the power of the electric motor unit 38 is not transmitted tothe engine E. Namely, the power of the electric motor unit 38 isutilized only for driving the compression unit 12 through the rotaryshaft 13.

[0022] A sealed space 27 is defined in the first and second pulleymembers 18 and 19. A second one-way clutch 44 is arranged on the rotaryshaft 13. The electric motor unit 38 includes a rotor 45 and a stator49. The rotor 45 is mounted on the rotary shaft 13 through the secondone-way clutch 44 in the sealed space 27. Namely, the second one-wayclutch 44 is arranged on a second power transmission path between therotary shaft 13 and the electric motor unit 38. The rotor 45 includes aniron core 45 a and a coil 45 b formed around the iron core 45 a. Thestator 49 is made of a magnet and is arranged around the outer peripheryof the rotor 45 in the sealed space 27. Therefore, when electric poweris supplied to the coil 45 b from an external device, the rotor 45 isrotated.

[0023] The second one-way clutch 44 includes a clutch mechanism 44 a anda bearing 44 b similarly to the first one-way clutch 31. With respect tothe predetermined rotational direction, the clutch mechanism 44 apermits power transmission from the rotor 45 to the rotary shaft 13, andblocks power transmission from the rotary shaft 13 to the rotor 45.

[0024] Therefore, when the electric motor unit 38 is started, in a statewhen the engine E is in the stopped state, the rotational power of therotor 45 is transmitted to the rotary shaft 13 through the secondone-way clutch 44. On the other hand, when the electric motor unit 38 isin the stopped state and the rotary shaft 13 is rotated by the drive ofthe engine E, the rotational power of the rotary shaft 13 is nottransmitted to the rotor 45. Therefore, a load on the engine E to drivethe rotor 45 is reduced.

[0025] Next, an exemplary control device that constitutes a preferredhybrid compressor system with the compressor C will be described. Asshown in FIG. 1, the control device for the compressor C includes an airconditioner ECU (Electric Control Unit) 51 that is similar to acomputer, or a controller, an information detector 52 for communicatingvarious information to the air conditioner ECU 51 and a driver 53 fordriving the electric motor unit 38. The air conditioner ECU 51 iselectrically connected to the information detector 52 and the driver 53.The information detector 52 includes various switches and varioussensors (not shown) for detecting air conditioning information, such asan air conditioning switch and a temperature sensor. The informationdetector 52 also includes a rotational speed sensor 52 a for detecting arotational speed Ne of the engine E, or for detecting a rotational stateof the engine E.

[0026] The air conditioner ECU 51 controls the switch of a drive source(electric motor unit 38/engine E) of the compressor C based on the airconditioning information and the rotational speed Ne of the engine Efrom the information detector 52. Namely, for example, when the vehicleis in an idle stop state (the engine E is in the stopped state), the airconditioner ECU 51 orders the driver 53 to start the electric motor unit38 based on air conditioning (cooling) request, and the drive source ofthe compressor C is switched from the engine E to the electric motorunit 38. When the vehicle is in a normal running state (the engine Eruns), the air conditioner ECU 51 orders the driver 53 to stop theelectric motor 53, and the drive source of the compressor C is switchedfrom the electric motor unit 38 to the engine E. The compression unit 12of the compressor C is a variable displacement type. When the engine Eruns and air conditioning is unnecessary, the air conditioner ECU 51changes the displacement of the compressor C to the minimum.

[0027] When the air conditioner ECU 51 switches the drive source of thecompressor C from the electric motor unit 38 to the engine E, the airconditioner ECU 51 performs a preferred sequence control according to apre-memorized program as shown in FIG. 2 through FIG. 3(b).

[0028] When the electric motor unit 38 is in the stopped state, therotational speed of the compressor C (the rotary shaft 13) is determinedbased on a pulley ratio between the power transmission mechanism PT andthe engine E and the information about the rotational speed Ne of theengine E from the rotational speed sensor 52 a. The pulley ratio betweenthe power transmission mechanism PT and the engine E is not one to one.For illustration purposes, however, the pulley ratio between the powertransmission mechanism PT and the engine E is assumed as one to one inthe present preferred embodiment.

[0029] As shown in FIG. 2, when the vehicle is in the idle stop state(the engine E is in the stopped state) and the compressor C is driven bythe electric motor unit 38, in a step S101, the air conditioner ECU 51monitors whether the starter motor S is started based on the informationabout the rotational speed Ne of the engine E from the rotational speedsensor 52 a. Namely, the air conditioner ECU 51 monitors whether theengine E is changed from the stopped state to a rotational state (adependent rotational state), more specifically, whether the rotationalspeed Ne of the engine E exceeds zero. If the judgment is NO in the stepS101, or if the rotational speed No is zero, it is continuouslymonitored whether the starter motor S is started.

[0030] If the judgment is YES in the step S101, it is judged that theengine E is changed from the stopped state to the rotational state. Theair conditioner ECU 51 orders the driver 53 to drive the electric motorunit 38 at a rotational speed Nm of a predetermined value γ in a stepS102. When the electric motor unit 38 runs at the predetermined value γof the rotational speed Nm, the electric motor unit 38 drives thecompressor C at a second predetermined rotational speed of thecompressor C that corresponds to a fourth rotational speed of the engineE. As shown in FIG. 3(b), the predetermined value γ corresponding to thefourth predetermined rotational speed of the engine E is higher than apredetermined value α of the rotational speed Ne of the engine E, or athird predetermined rotational speed of the engine E. The thirdpredetermined rotational speed of the engine E corresponds to a firstpredetermined rotational speed of the compressor C. The predeterminedvalue α is determined by the rotational speed of the starter motor S,that is, the predetermined value α corresponds to a theoreticalrotational speed of the compressor C (the rotary shaft 13) when thecompressor C is hypothetically driven by the starter motor S through theengine E. The theoretical rotational speed of the compressor C means arotational speed of the compressor C when the power is hypotheticallytransmitted from the engine E that is driven by the starter motor S tothe compressor C in a state that the electric motor unit 38 is in thestopped state. Namely, if the power is transmitted from the startermotor S to the compressor C through the engine E when the engine E isdriven by the starter motor S, the compressor C is driven by the startermotor S at the theoretical rotational speed.

[0031] In FIG. 3(b), it is shown that the rotational speed Nm of theelectric motor unit 38 is at the predetermined value γ even before thestarter motor S starts for easy understanding. However, the rotationalspeed Nm of the electric motor unit 38 practically varies in accordancewith a cooling load.

[0032] In a state when both the electric motor unit 38 and the engine Eare in a rotational state, the first one-way clutch 31 alternates thetwo drive sources in such a manner that the first one-way clutch 31permits power transmission from one drive source driving the compressorC at a higher speed than the other. Namely, when the electric motor unit38 is capable of rotating the rotary shaft 13 faster than the engine E,the electric motor 38 rotates the rotary shaft 13. When the engine E iscapable of rotating the rotary shaft 13 faster than the electric motorunit 38, the first one-way clutch 31 transmits the power from the engineE to the rotary shaft 13, and the engine E rotates the rotary shaft 13.Therefore, as mentioned above, when the electric motor unit 38 is drivenat the rotational speed Nm of the predetermined value γ during thestarting period of the engine E, the electric motor unit 38 drives thecompressor C. Therefore, a load for driving the compressor C, during thestarting period of the engine E, is applied to the electric motor unit38, not to the starter motor S.

[0033] In a step S103, it is judged whether the rotational speed Ne ofthe engine E exceeds a predetermined value β, or a predetermined value.As shown in FIG. 3(b), the predetermined value β is lower than thepredetermined value γ corresponding to the fourth predeterminedrotational speed of the engine E and is higher than the predeterminedvalue α of the rotational speed Ne of the engine E when driven by thestarter motor S. When the rotational speed Ne of the engine E exceedsthe predetermined value β, the engine E has successfully started up. Ifthe judgment is NO in the step S103, the process switches to the stepS102, and the rotational speed Nm of the electric motor unit 38 is keptat the predetermined value γ. Then, it is continuously monitored whetherthe engine E starts up in the step S103.

[0034] If the judgment is YES in the step S103, the process proceeds toa step 8104 where the air conditioner ECU 51 orders the driver 53 tostop the electric motor unit 38. Therefore, as shown in FIG. 3(b), therelationship between the rotational speed Ne of the engine E and therotational speed Nm of the electric motor unit 38 is inverted. As shownin FIG. 3(a) and FIG. 3(b), when the rotational speed Ne of the engine Ebecomes higher than the rotational speed Nm of the electric motor unit38, the drive source of the compressor C is automatically andimmediately switched from the electric motor unit 38 to the engine Ethrough the first one-way clutch 31 without an external control such asan electromagnetic clutch.

[0035] The following effects are obtained in the above-constructedpresent preferred embodiment.

[0036] (1) As mentioned above, the electric motor unit 38 is stoppedafter the engine E starts up. Therefore, due to the simple control, thedrive source of the compressor C is smoothly switched from the electricmotor unit 38 to the engine E without a break of air conditioning. Thesimplification of the control reduces a computing load on the airconditioner ECU 51.

[0037] (2) When the drive source of the compressor C is switched fromthe electric motor unit 38 to the engine E, the electric motor unit 38is stopped at a suitable time after the engine E starts up. Thispreferred operational sequence promotes startability of the engine E. Itis assumed that the electric motor unit 38 is stopped before the engineE starts up, or during the starting period of the engine E. In thiscase, the drive source is switched from the electric motor unit 38 tothe engine E during the starting period of the engine E. Therefore,startability of the engine E deteriorates. To avoid the problem, theelectric motor unit 38 is stopped after the engine E starts up in thepresent preferred embodiment.

[0038] Particularly, in the present preferred embodiment, the driver 53is ordered to drive the electric motor unit 38 at the rotational speedhigher than the theoretical rotational speed of the compressor C, whichdetermined by the rotational speed of the starter motor S, during thestarting period of the engine E. Therefore, the compressor C is drivenby the electric motor unit 38 during the starting period of the engineE. If the drive source of the compressor C is switched from the electricmotor unit 38 to the engine E (strictly the starter motor 8 for startingthe engine E) during the starting period of the engine E, a load on thestarter motor S increases. However, the drive source is switched fromthe electric motor unit 38 to the engine E after the engine E starts up.Therefore, the load on the starter motor 5 does not increase. As aresult, the startability of the engine E is satisfactory even by a smallstarter motor S.

[0039] The following alternative embodiments may be practiced accordingto the present invention.

[0040] When the drive source of the compressor C is switched from theelectric motor unit 38 to the engine E, the electric motor unit 38 isstopped as soon as the rotational speed Ne of the engine E exceeds thepredetermined value β in the present preferred embodiment. The electricmotor unit 38 may be stopped at a predetermined period after therotational speed No of the engine E exceeds the predetermined value β(for example with a timer), or the air conditioner ECU 51 may delays fora predetermined period to stop the electric motor E after the rotationalspeed Ne of the engine E exceeds the predetermined value β.

[0041] When the drive source of the compressor C is switched from theelectric motor unit 38 to the engine E, the electric motor unit 38 maybe stopped after the starter motor S starts up (the rotational speed Neof the engine E becomes equal to the predetermined value α). In thisalternative embodiment, the drive source of the compressor C is notswitched from the electric motor unit 38 to the engine E during aninitial period when the rotational speed of the starter motor S isincreased (when the rotational speed Ne is smaller than thepredetermined value α). Therefore, a load on the starter motor S can bereduced for starting the motor S, and the starter motor S can beminiaturized.

[0042] Although the roller type first one-way clutch 31 is used in thepreferred embodiment, the one-way clutch 31 may be changed to othertypes of one-way clutches such as, for example, a sprag type. The firstone-way clutch 31 may not include the bearing 31 b.

[0043] In the preferred embodiment, the electric motor unit 38 isinstalled in the power transmission mechanism PT. The electric motorunit 38 may be accommodated in the housing 11 with the compression unit12, or the electric motor unit 38 may be arranged separately from thecompressor C.

[0044] The compression unit 12 is not limited to the piston type. Thecompression unit 12 may be a scroll type, a vane type and a helicaltype.

[0045] Therefore, the present examples and embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein but may be modified within thescope of the appended claims.

What is claimed is:
 1. A hybrid compressor system comprising: a hybridcompressor for compressing refrigerant; a first drive source operativelyconnected to the compressor through a first power transmission path; asecond drive source operatively connected to the compressor through asecond power transmission path, the compressor being selectively drivenby one of the first drive source and the second drive source; a firstone-way clutch arranged on the first power transmission path between thecompressor and the first drive source for permitting power transmissionfrom the first drive source to the compressor; a driver for driving thesecond drive source; a sensor for detecting a rotational state of thefirst drive source; and a controller electrically connected to thedriver and the sensor, the controller, when a drive source of thecompressor is switched from the second drive source to the first drivesource, ordering the driver to stop the second drive source after therotation of the first drive source is detected.
 2. The hybrid compressorsystem according to claim 1, wherein the second drive source is anelectric motor.
 3. The hybrid compressor system according to claim 2,wherein the first drive source is an engine.
 4. The hybrid compressorsystem according to claim 3, wherein the controller orders the driver tostop the electric motor after the engine starts up.
 5. The hybridcompressor system according to claim 4, further comprising a startermotor operatively coupled to the engine.
 6. The hybrid compressor systemaccording to claim 5, wherein the controller orders the driver to drivethe electric motor, during a time when the starter motor starts theengine, such that the electric motor drives the compressor at a secondpredetermined rotational speed for blocking power from the startermotor, the second predetermined rotational speed being higher than afirst predetermined rotational speed, at which the compressor is drivenwhen the power is hypothetically transmitted from the starter motor tothe compressor through the engine in a state that the electric motor isin a stopped state.
 7. The hybrid compressor system according to claim6, wherein the sensor detects that the detected rotational speed of theengine exceeds a predetermined value.
 8. The hybrid compressor systemaccording to claim 7, wherein the controller orders the driver to stopthe electric motor when a detected rotational speed of the engineexceeds the predetermined value, the predetermined value ranging betweena third predetermined rotational speed of the engine that corresponds tothe first predetermined rotational speed of the compressor and a fourthrotational speed of the engine that corresponds to the secondpredetermined rotational speed of the compressor.
 9. The hybridcompressor system according to claim 8, wherein the controller delaysfor a predetermined period to stop the electric motor after the detectedrotational speed of the engine exceeds the predetermined value.
 10. Thehybrid compressor system according to claim 6, wherein the controllerorders the driver to stop the electric motor when the detectedrotational speed of the engine becomes equal to a third predeterminedspeed that corresponds to the first rotational speed of the compressor.11. The hybrid compressor system according to claim 1, furthercomprising a second one-way clutch arranged on the second powertransmission path between the compressor and the second drive source forpermitting power transmission from the second drive source to thecompressor.
 12. The hybrid compressor system according to claim 1,wherein the compressor is a piston type variable displacementcompressor.
 13. A method for switching a drive source of a hybridcompressor from a stopped state of an engine for running a vehicle to anormal running state, the compressor being operatively connected to theengine through a power transmission path, the compressor beingselectively driven by one of the engine and an electric motor, a startermotor being operatively connected to the engine, the method comprisingthe steps of: arranging a one-way clutch on the power transmission pathbetween the compressor and the engine; driving the compressor by theelectric motor during an idle stop state of the vehicle; detecting arotational speed of the engine; and driving the electric motor such thatthe electric motor drives the compressor at a second predetermined speedwhen the rotational speed of the engine is detected; and stopping theelectric motor when the detected rotational speed of the engine exceedsa predetermined value, wherein the predetermined value ranges between athird predetermined rotational speed of the engine that corresponds to afirst predetermined rotational speed of the compressor and a fourthrotational speed of the engine that corresponds to the secondpredetermined rotational speed of the compressor, the compressor beingdriven at the first predetermined rotational speed when power ishypothetically transmitted from the starter motor to the compressorthrough the engine in a state that the electric motor is in a stoppedstate.